Transfer Efficiency of Unsaturated Fatty Acids into Milk of Cows Fed Supplements of Cottonseed Protected from Ruminal Degradation

The strong link between saturated fat intake and increasing rates of coronary heart disease have provided the impetus for the dairy industry to provide milk with an increased proportion of polyunsaturated fatty acids. This can be achieved with the inclusion of protected lipid supplements in the diet of dairy cow. The protection from ruminal degradation is achieved by encapsulation of the lipid in a matrix of treated protein. In this study, feeding supplements of protected cottonseed (0, 1 and 2 kg/d) to lactating dairy cows significantly increased the amount of linoleic acid (C18:2) and stearic acid (C18:0) and decreased the proportion of oleic acid (C18:1 cis) in the milk. In addition, C18:2 increased and C18:1cis decreased proportionately in the plasma fatty acid profile, however C18:0 remained unchanged. There was no significant difference in the production parameters of milk yield, fat yield and protein yield between the treated and control groups. The transfer efficiency of C18:2 into milk was 45.2% and 36.5% for the 1 and 2 kg supplemented groups respectively. This high efficiency of transfer has resulted in the development of milk containing high levels of polyunsaturated fatty acids.